The sound of freedom: Propulsion flight provides thrust in wing's airpower

SEYMOUR JOHNSON AIR FORCE BASE, N.C. -- Have you ever been to an Air Show where a fighter aircraft surprises you with a low pass in full afterburner? There are ears screaming from the sound, skin burning from the heat and hearts jumping from the thrust. This is what the enemy must feel in his final moments ... fear, but to our brothers and sisters in arms, this is the sound of freedom.

The 4th Component Maintenance Squadron is the home of the largest
F-100-220 Propulsion Flight in the U.S. Air Force. The propulsion team, consisting of maintainers, contractors and civilians is responsible for on-equipment support of the 96 aircraft here as well as the off-equipment support and testing for more than 200 F100-PW-220/220E engines. This includes associated modules, secondary power systems and engine support equipment.

"As a crew, we work priority engines which are those closest to testing or those we can quickly rebuild," said Staff Sgt. Doug Rath, crew chief. "When we tear down engines, we are constantly ordering and turning in parts. We average about 20 parts per engine. However, some older engines will need over 100 parts changed out."

While this may seem simple, changing parts can be a complex task.

"Each engine is composed of five modules and about 25 components that are all changed at various times according to how many hours or cycles they have been flown," Sergeant Rath said.

With the help of the engine management branch from the 4th Maintenance Operations Squadron, maintainers must track close to 8,500 time-change parts.

On average, it takes seven days to rebuild an engine. Once the engine is completed, it is inspected twice before it is tested at test cell.

"At test cell, the engine is operated by a crew of three through its full range of power from idle to maximum augmentation," said Tech. Sgt. John Hamrick, test cell assistant NCO-in-charge. "One member operates the engine from inside a small cab, the second is a fire control monitor and the third performs visual inspections inside the bay next to the running engine."

The engine can reach temperatures of 970 degrees Celsius and can exert 23,770 pounds of thrust. When in augmentation the motor expends roughly 2 gallons of gas per second.

Upon successful completion of operational testing, the engine is towed back to the main propulsion facility where it is inspected three times for discrepancies by maintainers and quality assurance personnel. After passing the third inspection, the engine becomes a spare.

"I never get nervous when completing a final inspection on an engine before it becomes a spare," Sergeant Rath said. "I am confident that I have had the training and experience to prepare me for it."

The engine's final destination ... installed in an F-15E Strike Eagle parked on the ramp. "What is truly amazing is the people who are responsible for building these engines," said Master Sgt. Keith Mulligan, jet engine intermediate maintenance NCO-in-charge.

"The average age of our technicians is about 20. They are entrusted to produce a quality engine and ensure the safety of our aircrews ... not an easy burden to carry. It's amazing! After almost 20 years in the service, I still get chills when watching an engine run at test cell. It truly is the sound of freedom."